Tensioning device



March 20, 1962 L. SEIDL 'TENSIONING DEVICE 2 Sheets-Sheet 1 Filed May 19, 1960 INVENTOR.

LOlS SEIDL March 20, 1962 L. SEIDL 3,026,063

TENSIONING DEVICE Filed May 19, 1960 2 Sheets-Sheet 2 INVENTOR.

LOIS SEI DL T NEY United States Patent Ofiice 3,026,063 Patented Mar. 20, 1962 3,026,063 TENSIONING DEVICE Lois Seidl, Arnhem, Netherlands, assignor to American Enka Corporation, Enka, N.C., a corporation of Delaware Filed May 19, 1960, Ser. No. 30,135 Claims priority, application Netherlands May 25, 1959 1 Claim. (Cl. 242-155) This invention relates to the cording of yarns or threads, and relates to an improved apparatus for producing a cord from two single yarn threads, employing a novel yarn tension device.

In the production of cords for use in the manufacture of automobile tire fabrics, for example, two yarns or threads, hereinafter referred to as yarns, are as a rule plied together'to form a cord'having the desired characteristics with regard to strength, elongation, flex-life and resistance to abrasion, the plying being efiected in a single continuous operation. Normally in the plying operation a force is applied to the yarn components in order that they may have an equal and constant tension thereon at the point of plying or doubling whereby cords of uniform physical characteristics are obtained.

A device heretofore employed for applying tension on the yarn is one which comprises a tension or braking roller, a pressure roller cooperating with said braking roller, a housing enclosing said braking roller and pressure roller, and a stationary crown magnet arranged in said housing. The braking roller has connected thereto for rotation therewith a hysteresis disc which faces the crown magnet. In such a tension device a yarn is led between the braking roller and the pressure roller, with a spring urging the two rollers toward each other. The spring action is adjusted to such a value that the yarn cannot slip between the rollers but forces the rollers to rotate around their axes.

The rotation of the braking roller rotates the hysteresis disc relatively to the stationary crown magnet, thus causing said hysteresis disc to be regularly magnetized in difierent senses. The hysteresis losses occurring during changing of polarity in the hysteresis disc result in a braking couple acting opposite to the direction of rotation of the braking roller. This braking couple depends on various factors, such as the diameter of the crown magnet, the strength of the magnet, the width of the gap between the magnet and the hysteresis disc, and the material of the hysteresis disc.

An advantage of the above-described yarn tension device over other types of yarn tension devices resides in the fact that the tension applied to the yarn is independent, to a great extent, of the yarn velocit, since for each revolution of the braking roller the energy destroyed in the hysteresis disc is always constant and is independent of the speed with which the hysteresis disc rotates with respect to the stationary crown magnet.

In order to apply a constant tension on the yarn in this case it is necessary that no slip occur between the yarn and the braking roller. To this end the spring load on the pressure roller should be adjusted to a sufficiently high value. A similar eflect may be obtained by having the yarn first encircle the braking roller and, if required, then lead the yarn in between the pressure roller and the braking roller. The heretofore described tension devices are used particularly in an apparatus for the manufacture of a cord from two single yarns, said apparatus comprising a false-twisting spindle with a storage disc and a driving system, a top guide eye at the side of the false-twisting spindle remote from the driving system, a holding means for a yarn package between the storage disc and the top guide eye, as well as two yarn tension devices, one on each side of the falsetwisting spindle. In an apparatus of this type one yarn component of the cord to be formed is led through a yarn tension device, through the false-twisting spindle, ballooned across the storage disc, and through the top guide eye, and the other yarn component is led from a stationary package within the yarn balloon formed by said yarn component, through a second yarn tension de vice and through the top guide eye. In or close to the top guide eye the yarn components intertwine and form the cord.

In order to obtain a uniform cord it is necessary for the two yarn components to have an equal and constant tension at the point of doubling. For this purpose the hysteresis disc is particularly suitable, especially as regards the yarn tension device within the yarn balloon.

However, it has been found that this yarn tension device suffers from certain disadvantages which are evidenced particularly when using the same Within the yarn balloon employing the described apparatus in the manufacture of cords. In general a yarn tension device should be able to meet two requirements, to wit, it should be capable of applying a sufliciently large tension on the yarn and be of relatively small size. This latter characteristic is of importance if one aims at providing a small yarn balloon and therefore a small machine pitch and a low balloon tension. A small yarn balloon and a low balloon tension also mean a small energy consumption of the balloon. However, these requirements for the yarn tension device are in conflict with each other in the usual embodiment of the yarn tension device.

In apparatus of this type the pressure roller is at the side of the crown magnet and is mounted on a stub shaft in the brake housing. Accordingly, to obtain the desired tension, the diameter of the crown magnet should be large and that of the bralcng roller small. Moreover, to cause the pressure roller, which must have its rotation point outside the diameter of the crown magnet, to touch the braking roller, the diameter thereof should be large.

All this leads to undesira ly large dimensions of the yarn tension device.

It has been the practice, therefore, to have a braking roller of a larger diameter, namely a diameter of the same magnitude as that of the crown magnet. Thus, the diameter of the pressure roller becomes relatively smaller, which limits the dimensions of the yarn tension device. However, the larger diameter of the braking roller also means a smaller tension applying potential in the yarn tension device. In practice, it is sought to reach a compromise between the requirements of small dimensions on the one hand and a strong tension applying force on the other hand.

It is, accordingly, an important object of this invention to provide an improved yarn tension brake, in an apparatus for plying yarn to produce cords, which will be free from the foregoing disadvantages and which will be especially simple in construction and efficient in use.

Another object of this invention is the provision of a yarn tension device having a greater braking force than those heretofore employed in an apparatus for plying yarn to produce cords, and having smaller dimensions.

A further object of this invention is the use of the yarn brake of this invention in an apparatu for the manufacture of a cord from two single yarns, said apparatus comprising a false-twisting spindle with a storage disc and a driving system, a top guide eye at the side of the false-twisting spindle remote from the driving system, a holding means for a yarn package between the storage disc and the top guide eye, as well as two yarn tension devices, one on each side of the false-twisting spindle, whereby several of these apparatuses with smaller machine pitch may be mounted and whereby a higher machine speed may be obtained.

It is also an object of this invention to provide a novel method of manufacturing a cord from two single yarns. A further object of this invention is the provision of highly uniform cords having a compactness which is of lower degree than cords made by prior methods.

@ther objects and advantages of this invention will appear from the following detailed description.

In its broadest aspect, the yarn tension device of this invention includes a pressure roller rotatably mounted on a shaft supported at a point remote from the crown magnet. Thus, one end of the shaft of the pressure roller is journalled in a hearing at the free end of an arm pivotally mounted on the housing of the tension device on the side opposite to that on which the crown magnet is positioned. In fact, it is possible to arrange the shafts of the pressure roller and the braking roller very close together. This offers the advantage that both the braking roller and the pressure roller may be of smaller diameter with the result that the tension applying force is increased and the dimensions of the yarn tension device are reduced.

It has been found that when using a yarn tension device according to this invention on a known appaartus for the manufacture of cords, the speed of this apparatus may actually be increased by 40%, the machine pitch remaining constant. This increased speed results in a required increase of the necessary tension applying force by about 100%. However, it was found at the same time that the yarn balloon and, with the balloon, also the machine pitch, could still be reduced.

With the yarn tension device according to this invention, various embodiments of the pivot arm and of the spring arrangement for forcing the pressure roller against the braking roller are conceivable. For example, the pivot point of the pivot arm on the tension device housing may consist of a pin fixed to the pivot arm, said pin being rotatable in said housing. In that case, the spring forcing the pressure roller against the braking roller may be identical to that of known yarn tension device wherein an expansible spring is secured to one end to the pivot arm and to the other end to the housing. However, this latter expedient is disadvantageous for the reason that the spring load cannot be adjusted in a simple and reproducible manner.

This disadvantage is overcome if, according to this invention, the pivot point of the pivot arm is formed by a hub on the pivot arm and a pivot pin rigidly secured to the tension device housing, and further coupling the hub and the pivot pin in driving relationship by a torsion spring wound around the hub. In this way a particularly compact design of yarn tension device is obtained where- 'in the torsion spring may be adjusted in a very simple and reproducible manner. The tensioning of the torsion spring may be effected by making the connecting point of this spring to the pivot arm adjustable. However, the possible range of this adjustabi-lity is small so that, in order to be able to realize a wide range of adjustability, a stiff spring is required. This presents another disadvantage in that the pressure force of the pressure roller very rapidly increases on withdrawing said pressure roller from the braking roller. As a result the threading-in of a yarn between the two rollers is difiicult.

It has now been found that said difiiculty may be avoided if, according to this invention, the connection of the torsion spring to the pivot pin is adjustable. This s adjustability may, for example, be effected by securing the torsion spring to a nut and by providing an additional locking nut for attaching the hub of the pivot arm on the pivot shaft. Instead of a nut with a locking nut many other solutions'may, of'course, be employed such as, for example, -a friction disc with locking nut, or a friction disc' with a toggle locking system. Since these means for securing'the torsion'spring to the pivot pin may be rotatable around said pivot pin almost without limitation, the torsion spring may also be of a type having a moderately stiff spring characteristic. This ofiers the advantage that the force of the pressure roller against the braking roller hardly increases if, in order to guide the yarn in between the rollers, one withdraws the pressure roller somewhat from the braking roller. More over, with this construction it is much simpler to adjust the force of the rollers acting against each other in a very accurate and reproducible way.

The two rollers of the tension device are prefer-ably given the shape of truncated circular cylinders. With this construction of the rollers it is possible for a yarn to move laterally from between the rollers during the plying operation. In order to prevent this it is necessary either to keep the yarn in its path by means of thread guides or to make the rollers very wide.

Another difficulty experienced with the cylindrical shape of the rollers consists in the danger of the yarn slipping through. In order to prevent the yarn from slipping between the two rollers the pressure on the rollers may be increased up to a certain limit. It has been found, however, that beyond a certain value of the pressure force a further increase thereof has no or at least almost no additional effect on the action of the pair of rollers to prevent yarn slippage. However, it has been surprising to find that a very much improved action of the pair of rollers toward prevention of slippage is obtained with a lower pressure force of the pressure roller against the braking roller, if the pressure roller and/or the braking roller is shaped like a double cone tapering towards the end and having a cylindrical intermediate portion. It was also surprisingto find that with this shape of one or both rollers the yarn shows no tendency to run off laterally from between the pair of rollers. According to this invention a conicity of which the top angle of the conical surfaces amounts to about 1 was found to give desirable results.

Preferably the material of the rollers mostly consists of a more or less elastic material. This presents the advantage that the machining of the roller surfaces need not be so accurate in order still to obtain auniform contact, and that, moreover, the transmission of forces from the braking roller onto the yarn is more uniform so that consequently the risk of the yarn getting damaged is avoided.

It is known in the yarn plying art to reduce the slip between a yarn and a braking roller by pressing the yarn with a pressure roller against a braking roller. It is also known that the same effect may be obtained by leading the yarn with one or more windings around the braking roller, in combination with the step of guiding the yarn around a small pulley roller. In the case of this latter arrangement it is known that, if at least one point of the encircling yarn does not slip across the braking roller, the running-on point of the yarn on the roller is among these points. It would be obvious then to expect that a combination of an encirclement of the yarn around the braking roller with a pinching of this yarn against the braking roller by means of a pressure roller would be the most effective if the yarn would be passed first around the braking roller and thereafter would be led in between the braking roller and the pressure roller. The encirclement of the yarn around the braking roller is then effected at a lower tension level than in the case of the yarn first being pinched and thereafter being passed around the braking roller.

In the first case one might consequently consider it to be more probable that the runningon point of the yarn will not slip across the braking roller. It was surprising to find the reverse to be true, namely that a better trans- .mission of forces from the braking roller onto the yarn is obtained by passing said yarn first between the rollers and subsequently around the braking roller;

The apparatus and method of this invention produce a highly desirable cord. Thus, the cords obtained are found to be highly uniform, with the compactness thereof being less than that of the cords manufactured in accordance with prior practice. The smaller compactness is a result of the lower yarn tension with which the yarns are doubled to a cord, said lower yarn tension in turn being an effect of the operation of the apparatus of this invention with a smaller yarn balloon. The fact that the cords thus obtained are less compact is of particular importance where these cords are used in the manufacture of automobile tire fabric. It is found that the dimensional stability of the cord and the adhesion of rubber to the cord may be improved within certain limits if the compactness of the cord is decreased.

In the accompanying drawings wherein preferred embodiments of a yarn tension device according to the invention and of an apparatus for the manufacture of cords employing said yarn tension device are shown:

FIG. 1 shows diagrammatically an embodiment of an apparatus for the manufacture of a cord,

FIG. 2 is a front view, on an enlarged scale and partly broken away, of the yarn tension device which as shown in FIG. 1 is provided within the balloon,

FIG. 3 is a side view, partly in section, of said yarn tension device, and

FIG. 4 is a side view, partly in section, of the yarn tension device showing the system of the crown magnet and the hysteresis disc.

Like reference numerals indicate like parts throughout the several views of the drawings.

Referring now to the drawings for a detailed description of the yarn tension device of this invention and the apparatus in which it is used, the reference numerals 1 and 2 shown in FIG. 1 indicate supply packages from which single yarns 3 and 4, respectively, are fed to a junction or ply point 5 where they are plied or twisted together to form a cord 6. The resulting cord passes through a guide eye 7 and is collected on a suitable take up means (not shown).

The yarn 3 coming from package 1 is led through a guide eye 11 and an adjustable tension device 12 to a guide eye 13. From guide eye 13 the yarn 3 passes through a hollow spindle 14, the axis of which is inclined to the vertical axis of yarn package 1. The hollow spindle 14 is mounted for rotation by conventional means, the rotation thereof being effected by the belt and driving pulley means 14 commonly employed for this purpose. Integral with the hollow spindle 14 is a disc 16 having therein a radial passageway 17 through which yarn 3 passes. The yarn 3 after leaving passageway 17 travels in contact with a disc 18 carried by disc 16 and then freely balloons, the balloon terminating at ply point 5 P where the yarn 3 is corded with yarn 4 from package 2.

The yarn package 2 is mounted on a support 19 in such a manner that the axis thereof is inclined to the axis of yarn package 1, i.e. it is coaxial with the axis of the spindle 14. The support 19 is so constructed and arranged that it remains stationary on rotation of the hollow spindle 14 and disc 16. A protecting hood 29, carried by support 19, is provided with a pivoted cover it A yarn guide 8 is disposed in said cover 10, and the yarn tension device 9, which acts on yarn 4 in its travel to ply point 5, is suitably fixed to said cover 16.

The guide 7 is vertically adjustable so that the position of ply point is predeterminable. By changing the position of the guide eye 7 relative to the yarn tension device 9 and by changing the degree of tension applied by the tensioning device 9, the tensions in the yarn components and the size of the yarn balloon may be controlled. It is preferred to operate with low yarn tensions in yarns 3 and 4 and with a small yarn balloon. For this purpose the guide eye 7 is arranged as low as possible and the shape of the cover and of the yarn tension device 9 are so select d that they adapt themselves as well as possible to the yarn balloon.

In FIGS. 2, 3 and 4 where the yarn tensioning device 9 is more particularly shown, it will be seen that it comprises a housing of two sections 21 and 22 which are secured to each other by means of screws 23. Mounted for rotation on said housing is a braking roller 24, and a pressure roller 25 which is arranged to be in operative contact with said braking roller. I

The pressure roller 25 is rotatably carried by an arm 26 which is pivotally mounted on a pin 27 fixed to section 21 of the housing, as is shown in FIG. 3. The free end of pin 27 is provided with a conical surface 28 and an integral threaded extension 29. Threaded on the extension 29 into contact with the conical surface 28 is a friction disc 30 which is held in position on said pin 27 by a lock nut 31. To maintain the pressure roller 25 in contact with the braking roller 24 there is provided a torsion spring 32 which is mounted on and around friction disc 3t) and extends onto the hub end 33 of the pivot arm 26, the end 34 of the torsion spring being received in a recess 35 in the pivot arm.

In order to adjust the pressure of the pressure roller 25 on braking roller 24, the lock nut 31 is loosened, the friction disc 39 is turned on pin 27 until the desired pressure is attained, and the lock nut again tightened. The pressure roller is preferably divided in an axial direction into three zones of which the middle zone is cylindrical. The two outer Zones are conical with a top angle of 1. In view of the very slight taper on the ends of this roller, the same has been omit-ted from the drawings.

The braking roller and the pressure roller are preferably covered with a material having a hardness of shore. This covering material, as is indicated above, may be a rubber-like modification of a polyurethane which is available on the market under the name of Vulkollan.

For the purpose of guiding yarn 4 to the desired position between the braking roller and the pressure roller, there is provided a guiding funnel 36 which is attached by screws 37 to section 23 of the housing, which funnel guides the yarn centrally between said rollers. The yarn '4 is led to said funnel through the yarn guiding member 8 in the cover in of the hood 2t], and then through tubular guiding member 33. The yarn 4, after passing through funnel 36, passes between and through braking roller 24 and pressure roller 25, around braking roller 24 and then around a small reversing roller 39 having the shape of a double cone, and then to the ply point 5. The reversing roller 39 is mounted for rotation at the top of section 21 of the housing. A recess 49 is provided in the housing near the reversing roller 39 to prevent contact of the yarn 4 with the housing.

In FIG. 4 there is shown the means for applying constant tension on yarn 4. T 0 this end the housing section 22. is provided with a crown magnet 41, the spacing between the poles of which is filled with a suitable synthetic resin whereby there will be no accumulation of dirt and dust. A shaft 42, having a screw threaded portion 43, is carried by housing section 22 and is locked in position by means of a nut 44 of polyamide material such as nylon and locking pin 45. This shaft arrangement permits axial movement of the shaft without any loosening of the nut 44 and prevents any rotational movement of said shaft. The braking roller 24 is journalled on said shaft.

The braking roller 24 has at its inside edge thereof, i.e. the edge within the housing section 21, a flange 46. This flange seals the housing against the entry of dirt, dust and other foreign matter. Secured to flange 46 is an annular hysteresis disc 47 which faces the poles of crown magnet 41.

As the hysteresis disc rotates, the rotation being efiected by the movement of braking roller 24, a drag is generated on the hysteresis disc in a constant pattern, resulting in a constant tension on yarn 4. The tension on the yarn may be altered by changing the width of the gap between the poles of the crown magnet and the hysteresis disc.

7 This may be done by axially adjusting the shat 42 relative to the housing.

The yarn tension device of this invention permits greater tension to be applied on the yarn, while the tension device per se is of smaller dimension than those heretofore employed. Moreover, the triangular form of the tension device fits easily within the balloon of the yarn 3. Accordingly, the balloon of yarn may be of smaller dimen- While preferred embodiments of the invention have been described, it is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined by the following claim.

What is claimed is:

A yarn tension device comprising a housing, a cylindrically shaped crown magnet fixed within said housing, a stub shaft secured to said housing coaxially of said crown magnet and extending outwardly thereof, a braking roller journalled to said stub shaft for rotation relative thereto, said braking roller having a diameter less than said crown magnet, a hysteresis disc secured to said braking roller for rotation therewith and mounted inside said housing coaxially of said stub shaft adjacent to but spaced from said crown magnet, means for adjusting stub shaft relative to said housing for permitting variation in the spacing between said hysteresis disc and said crown magnet, a pressure roller adapted to engage and cooperate with said braking roller, an arm supporting said pressure roller for rotation and for transverse movement, means attached to said housing for pivotally supporting said arm and for urging said pressure roller into engageent with said braking roller, a funnel for guiding yarn into atthroat between said pressure roller and said braking roller, a tubular member for guiding yarn from a source of supply to said funnel, and means for Wrapping yarn passing between said pressure and braking rollers about a major portion of the peripheral surface on said braking roller to prevent slippage;

References Cited in the file of this patent UNITED STATES PATENTS Klein June 7, 1960 

